Materials Literature
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For V-shaped surface grooves in copper, we have obtained the capillary driven flow kinetics for two liquids: unreactive 1-heptanol and eutectic Sn/Pb solder, which is known to react with copper. We show experimentally that the flow of both liquids in these grooves follows the classical Washburn kinetics, i.e., a Poise…
Controlled molecular weight, thermoplastic polyimides have been prepared via poly(amic acid) salt precursors. 2,2-Bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride and m -phenylenediamine (the Ultem monomers), together with calculated amounts of phthalic anhydride were reacted in N -methylpyrrolidinone as well as…
A set of synthetic and natural chabazite materials with compositions ranging from Si/Al = 2.6−7.6 have been obtained. Detailed studies using multinuclear MAS NMR have been used to analyze the distribution of aluminum within the crystalline framework. Comparison of the observed 29 Si NMR results to those predicted by v…
The high-spin → low-spin relaxation dynamics of the Fe(III) spin-crossover complexes [Fe(Sal 2 tr)]PF 6 (H 2 Sal 2 tr = Bis(salicylaldimino)triethylenetetramine) and [Fe(acpa) 2 ]PF 6 (Hacpa = N -(1-acetyl-2-propylidene)-2-pyridylmethylamine) are discussed within the theory of nonadiabatic multiphonon relaxation. A Hu…
A comprehensive study of 8 mol% yttria-stabilised zirconia has been made between 150 and 1000 °C, using ac impedance spectroscopy and high-temperature neutron powder diffraction. It has been demonstrated that the conductivity anomaly, which occurs at ca. 650 °C, is structural in origin. A sharp decrease in the activat…
Some spinel ferrites (MnxFe3 –xO4; x= 0, 0.5, 1.0, 1.5) have been synthesized at 70 °C by the method of precipitation, for electrochemical characterization as oxygen anodes. The electrodes were prepared as films on a nickel substrate by painting with an oxide-slurry, followed by sintering at 400 °C. The electrocatalyt…
Cadmium sulfide and cadmium selenide nanoparticles have been synthesised by a novel route involving the thermal decomposition of the bisdiethyldithio- or bisdiethyldiseleno-carbamates of cadmium in refluxing 4-ethylpyridine solutions. The nanodispersed materials were studied by electronic spectroscopy and bandgaps wer…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTConduction and Valence Band Edges of Porous Silicon Determined by Electron TransferJulie M. Rehm, George L. McLendon, and Philippe M. FauchetView Author Information Department of Chemistry, University of Rochester Rochester, New York 14627 Department of Chemistry, Prin…
The origin of the host−guest interaction energy between R−CN molecules (R = CH 3, C 6 H 5 ) and the basket-like cavitand (V 12 O 32 ) 4- has been investigated by means of ab initio Hartree−Fock calculations on the model system [HCN⊂(V 12 O 32 ) 4- ] and on the two observed complexes. The computed stabilization energie…
In the production of 3D fabrics for textile-based composite material applications, the conventional 2D weaving device is employed to produce interlaced 3D fabric comprising two sets of yarns, and non-interlaced 3D fabric constituting three sets of yarns. While the process of producing interlaced 3D fabric comprising t…
The molecular dynamics of a series of diphenylethyne- or diphenylbutadiyne-linked porphyrin arrays in solution at 296 K have been investigated using high-field proton NMR spectroscopy. Measurements of the direct dipolar interactions between vicinal proton pairs located on the pyrrole and phenylene moieties provide inf…
It has been thought that the conductivity of pure water is high enough to neglect the streaming electrification. However, with the recent advancement of semiconductor industries, ultrapure water appeared to cause electrification problems at the washing and the rinsing processes of semiconductor wafers. The investigati…
Thin films of poly[Ru(vbpy) 2 (py) 2 ] 2+ (vbpy is 4-vinyl-4‘-methyl-2,2‘-bipyridine; py is pyridine) have been deposited on electrodes by reductive electropolymerization. Photolysis of the films in the presence of chloride ion leads to photochemical loss of the pyridine ligands and sequential formation of poly[Ru(vbp…
Two examples of a new family of water-based, nonstick, hydrophobic polymeric coatings were used to relate wettability to surface composition and adhesion. They were prepared by cross-linking reactive perfluoroalkyl polymeric surfactants, RPPSs, with poly(2-isopropenyl-2-oxazoline). Wettability may be manipulated by va…
The ability of poly(ethylene glycol)s, PEGs, to control poly(3-hydroxybutyrate), P3HB, molecular weight in a microbial fermentation polymerization process was studied using Alcaligenes eutrophus with fructose as the sole carbon source. PEGs varying in molecular weight and end group functionality were added to the cult…
The conformational behaviour of a series of monohydroxamic acids, p-RC6H4CONR′OH (R = Me, R′= H, Me; R = MeO, R′= H, Me; R = NO2, R′= H), and a series of dihydroxamic acids, (CH2)n(CONR′OH)2(n= 3–8, 10, R′= H and n= 7, R′= Me), in methanol, DMSO and chloroform and in the solid state has been examined using IR and NMR…
Layered niobates K 4 Nb 6 O 17 and KNb 3 O 8 showed bright blue emission at 77 K. The luminescent properties were changed by exchanging potassium ions at interlayers with other cations. The luminescent intensity of NH 4 + -exchanged K 4 Nb 6 O 17 was higher than that of native K 4 Nb 6 O 17 . In contrast, for H + -exc…
Oxygen-17 NMR studies indicated that the hexametalates [MW5O19]n– or their derivatives [(MeO)MW5O18](n–1)–(M = Ti, Zr, V, Nb, Ta, Mo or W) can be obtained by hydrolysis of the appropriate mixture of metal alkoxides in the presence of M′O42–(M′= W or Mo) with remarkable selectivity in some cases, giving a very efficien…
The insulation of the 400 kV transmission lines located in the northeast part of Mexico (Monterrey) have experienced flashover problems due to pollution accumulation. Several actions have been taken to increase reliability (washing, use of RTV coatings, insulators with longer leakage distance, etc.). In order to help…
A systematic survey of zeolites Y containing tris(2,2‘-bipyridine)ruthenium(II) with various levels of loading was undertaken. Almost pure Ru(bpy) 3 2+ was obtained whenever the loading was less than approximately one complex per two supercages. At higher loading an increasing amount of byproducts corresponding formal…